Polypropylene composition, process for preparing the same, and polymerization catalyst therefor

ABSTRACT

A polypropylene composition comprising 0.001 to 10 parts by weight of a polyethylene having an intrinsic viscosity [etaE] of 0.01 to less than 15 dl/g s measured in tetralin at 135° C. and 100 parts by weight of a polyolefin comprising at least polypropylene, wherein the polyethylene is finely dispersed as particles with a number average particle diameter of, e.g., 1 to 5000 nm in the polyolefin comprising at least polypropylene. By virtue of the above constitution, the polypropylene composition has excellent transparency and rigidity, is free from the creation of a sweeper roll flow mark in the preparation of a film and substantially free from a neck-in phenomenon of a film, and has high productivity.

TECHNICAL FIELD

The present invention relates to a polypropylene composition thatprovides excellent productivity for polypropylene film and from which afilm having high transparency and high rigidity can be obtained, and amethod for producing the same, and to processes for preparing a catalystand a preactivated catalyst for polypropylene production used in themethod. More particularly, the present invention relates to apolypropylene composition from which a non-oriented polypropylene filmexcellent in transparency and rigidity and having high productivity, inwhich little neck-in is caused and on which a sweeper roll mark is noteasily formed in producing a thick polypropylene film having a thicknessof 30 μm or more, can be produced, and to a method for producing thesame, and to processes for preparing a catalyst and a preactivatedcatalyst for polypropylene production used in the method.

BACKGROUND OF THE INVENTION

Since crystalline polypropylene is excellent in mechanical properties,chemical resistance and the like, and is very useful with respect tocost effectiveness, it has been widely utilized in every molding field.In particular, it is excellent in optical properties, mechanicalproperties, packaging suitability and the like, and it has been widelyused as packaging materials for food, fiber wrapping and the like.

However, when producing a polypropylene film at a high speed using aconventional polypropylene resin, there may be problems. First, neck-in,in which the width of the resin film molded with a T die narrows so muchthat the width of the film having uniform thickness is reduced, canoccur. This is economically inefficient. Second, a spiral mark may betransferred onto the film due to the use of a sweeper roll to prevent aslipping agent such as fatty amide, which is generally added to apolypropylene resin, from being deposited on a chilled roll surface. Asa result, optical properties of the film are lowered and theproductivity is greatly reduced. Particularly in production of a thicknon-oriented film, a sweeper roll mark may be transferred onto the filmand causes irregular transparency in the optical property, so that theproductivity of a film having high transparency is limited.

A method of copolymerizing α-olefins such as propylene, ethylene andbutene-1 is generally carried out in order to improve transparency in anon-oriented polypropylene film. However, when producing a non-orientedfilm by melt extrusion with a T die using the random copolymer obtained,because the random copolymer is low in crystallization temperature andin crystallization rate, it is not solidified by the time it iscontacted with a sweeper roll. As a result, a spiral mark is easilytransferred onto the film due to the sweeper roll, so that a film havinga desirable high and uniform transparency is difficult to obtain,especially in producing a thick film. In addition, because thenon-oriented film obtained is low in rigidity, elongation or dimensionalchange may occur when conducting printing on the film at a high speedand the product value is reduced.

Methods of adding metallic salts such as aluminum carboxylate (JapanesePublished Unexamined Patent Application (Tokukai) No. HEI 3-220208), oradding nucleating agents such as a sorbitol type derivative, organicphosphate and the like (Japanese Published Unexamined PatentApplications (Tokukai) No. SHO 51-22740 and No. SHO 58-225143, and thelike) to a polypropylene resin are used in order to improve transparencyand rigidity of the polypropylene resin. However, there are problems inany of these methods as follows: insufficient dispersion of a nucleatingagent may cause a reduction in product quality, and in some cases anodor remains in the modified propylene obtained and the odor istransferred to packaging materials for food and reduces the food productvalue.

In order to solve this problem, use of nucleating agents made of polymerwith a high melting point have been proposed (Japanese PublishedUnexamined Patent Applications (Tokukai) No. SHO 60-139710, No. SHO62-1738 and No. HEI 1-156305, and the like). However, there wereproblems in these methods such as the high cost of the nucleating agentsof polymer with high melting point used, or that sufficient propertieswere not always observed depending upon the use. Thus, improvements inthese methods have been required.

Furthermore, a method comprising preliminarily polymerizing α-olefinhaving 2 or more carbon atoms in the presence of a catalyst comprising atitanium complex and an organic metal compound, and then polymerizingα-olefin having 3 or more carbon atoms (Japanese Published ExaminedPatent Application (Tokko) No. HEI 5-58003), a method of using apreactivated catalyst for α-olefin polymerization formed by allowing acatalyst comprising a titanium trichloride composition and an organicaluminum compound to react simultaneously with α-olefin and an electrondonor (Japanese Published Unexamined Patent Application (Tokukai) No.SHO 61-64704), a method which comprises polymerizing olefin afterpreliminary polymerization of 0.01 to 1 g of olefin per a solid catalystcomposition (Japanese Published Unexamined Patent Application (Tokukai)No. SHO 57-151602), and the like have been proposed to improve thetransparency and rigidity of polypropylene resins. However, thepreliminarily polymerized poly-α-olefin did not have a proper intrinsicviscosity [η] in any of these methods. Therefore, if a polypropylenefilm is produced by using a polypropylene resin obtained by suchmethods, the transparency and rigidity of the polypropylene film may begreatly reduced.

In the various compositions and the methods for producing the same whichhave been proposed as mentioned above, transparency and rigidity ofpolyolefin are improved to a certain degree. However, problems withregard to odor due to nucleating agents, crystallization rate, thermalstability and the like still remain to be solved. Particularly inproduction of thick films, detailed studies have not been carried out soas to provide all of high transparency, high rigidity and highproductivity.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a polypropylenecomposition from which a polypropylene film excellent in transparencyand rigidity and having high productivity can be obtained, a method forproducing the same, and processes for preparing a catalyst and apreactivated catalyst for polypropylene production used in the method.

As a result of researches so as to accomplish the above-mentionedobject, the inventors have completed this invention.

A polypropylene composition of the present invention comprises:

(a) 0.001 to 10 weight parts of polyethylene having an intrinsicviscosity [ηE] of at least 0.01 dl/g but less than 15 dl/g measured intetralin at 135° C.; and

(b) 100 weight parts of polyolefin comprising at least polypropylene;wherein

(c) said polyethylene exists as dispersed fine particles in saidpolyolefin comprising at least polypropylene.

In the polypropylene composition of the present invention, it ispreferable that the polyethylene exists as dispersed fine particleshaving a number average particle diameter of 1 to 5,000 nm.

In the polypropylene composition of the present invention, it is furtherpreferable that the number average particle diameter of the polyethyleneis 10 to 500 nm.

In the polypropylene composition of the present invention, it ispreferable that the intrinsic viscosity [ηE] of the polypropylenecomposition measured in tetralin at 135° C. is 0.2 to 15 dl/g.

In the polypropylene composition of the present invention, it ispreferable that the polyolefin comprising polypropylene is either apropylene homopolymer or an ethylene-propylene copolymer containing 0.05to 3 weight % of ethylene.

In the polypropylene composition of the present invention, it ispreferable that the density of the polyethylene (a) is 0.93 to 0.960g/cm³.

In the polypropylene composition of the present invention, it ispreferable that the content of the polyethylene (a) is 0.004 to 10weight parts. This range of composition is preferable when conductingthe main polymerization of polypropylene after preliminarypolymerization of polyethylene.

In the polypropylene composition of the present invention, it ispreferable that the content of the polyethylene (a) is at least 0.001weight parts but less than 0.05 weight parts, more preferably either atleast 0.004 weight parts but less than 0.05 weight parts, or at least0.05 weight parts but less than 10 weight parts. This range of thepolyethylene composition is preferable for a composition whereinpolypropylene is first polymerized and thereafter melt mixing with aseparately-produced polyethylene is performed.

A method for producing a polypropylene composition according to thepresent invention comprises polymerizing 100 weight parts of olefincomprising at least propylene in the presence of 0.001 to 10 weightparts of a preactivated catalyst comprising: a catalyst for polyolefinproduction comprising a transition metal compound catalyst compositioncontaining at least a titanium compound, 0.01 to 1,000 mol of an organicmetal compound (AL1) of a metal selected from the group consisting ofmetals that belong to group I, group II, group XII and group XIII of theperiodic table published in 1991 per 1 mole of the transition metalatom, and 0 to 500 mol of an electron donor (E1) per 1 mol of thetransition metal atom; and 0.01 to 5,000 g of polyethylene (A) having anintrinsic viscosity [ηA] of at least 0.01 dl/g but less than 15 dl/gmeasured in tetralin at 135° C. per 1 g of the transition metal compoundcatalyst composition, and allowing the polyethylene to be finelydispersed as particles in the polyolefin composition.

In the method for producing a polypropylene composition according to thepresent invention, it is preferable that the polyethylene exists asdispersed fine particles having a number average particle diameter of 1to 5,000 nm.

In the method for producing a polypropylene composition according to thepresent invention, it is further preferable that the number averageparticle diameter of the polyethylene is 10 to 500 nm.

In the method for producing a polypropylene composition according to thepresent invention, it is preferable that the intrinsic viscosity [ηE] ofthe polypropylene composition measured in tetralin at 135° C. is 0.2 to15 dl/g.

In the method for producing a polypropylene composition according to thepresent invention, it is preferable that the polyolefin comprisingpolypropylene is either a propylene homopolymer or an ethylene-propylenecopolymer containing 0.05 to 3 weight % of ethylene.

In the method for producing a polypropylene composition according to thepresent invention, it is preferable that the density of the polyethylene(a) is 0.93 to 0.960 g/cm³.

A process for preparing a preactivated catalyst for olefinpolymerization according to the present invention comprises polymerizingolefin in the presence of a catalyst for polyolefin productioncomprising a transition metal compound catalyst composition containingat least a titanium compound, 0.01 to 1,000 mole of an organic metalcompound (AL1) of a metal selected from the group consisting of metalsthat belong to group I (e.g. Li and Na), group II (e.g. Mg), group XII(e.g. Zn) and group XIII (e.g. Al) of the periodic table published in1991 per 1 mole of the transition metal atom, and 0 to 500 mole of anelectron donor (E1) per 1 mole of the transition metal atom topreliminarily activate the catalyst and form 0.01 to 5,000 g ofpolyethylene (A) having an intrinsic viscosity [ηA] of at least 0.01dl/g but less than 15 dl/g measured in tetralin at 135° C. per 1 g ofthe transition metal compound catalyst composition, wherein thepolyethylene (A) is supported by the transition metal compound catalystcomposition.

A catalyst for the main olefin polymerization according to the presentinvention comprises: a preactivated catalyst for olefin polymerizationobtained by a method comprising polymerizing olefin in the presence of acatalyst for polyolefin production comprising a transition metalcompound catalyst composition containing at least a titanium compound,0.01 to 1,000 mole of an organic metal compound (AL1) of a metalselected from the group consisting of metals that belong to group I,group II, group XII and group XIII of the periodic table published in1991 per 1 mole of the transition metal atom, and 0 to 500 mole of anelectron donor (E1) per 1 mole of the transition metal atom topreliminarily activate the catalyst and form 0.01 to 5,000 g ofpolyethylene (A) having an intrinsic viscosity [ηA] of at least 0.01dl/g but less than 15 dl/g measured in tetralin at 135° C. per 1 g ofthe transition metal compound catalyst composition, wherein thepolyethylene (A) is supported by the transition metal compound catalystcomposition; an organic metal compound (AL2) of a metal selected fromthe group consisting of metals that belong to group I, group II, groupXII and group XIII of the periodic table published in 1991, the totalamount of the organic metal compound (AL2) combined with the organicmetal compound (AL1) contained in the preactivated catalyst being 0.05to 5,000 mole per 1 mole of the transition metal atom in thepreactivated catalyst; and an electron donor (E2), the total amount ofthe electron donor (E2) combined with the electron donor (E1) containedin the preactivated catalyst being 0 to 3,000 mole per 1 mole of thetransition metal atom in the preactivated catalyst.

A method for producing a polyolefin composition according to the presentinvention comprises producing polypropylene having an intrinsicviscosity [ηP] of at least 0.01 dl/g but less than 15 dl/g measured intetralin at 135° C. in the presence of said catalyst for main olefinpolymerization.

A method for producing a polypropylene composition according to thepresent invention comprises producing polypropylene in the presence of apreactivated catalyst comprising: a catalyst for polyolefin productioncomprising a transition metal compound catalyst composition containingat least a titanium compound, 0.01 to 1,000 mole of an organic metalcompound (AL1) of a metal selected from the group consisting of metalsthat belong to group I, group II, group XII and group XIII of theperiodic table published in 1991 per 1 mole of the transition metalatom, and 0 to 500 mole of an electron donor (E1) per 1 mole of thetransition metal atom; and 0.01 to 5,000 g of polypropylene having anintrinsic viscosity [ηA] of at least 0.01 dl/g but less than 15 dl/gmeasured in tetralin at 135° C. per 1 g of the transition metal compoundcatalyst composition, and performing melt mixing of the polypropylenewith polyethylene.

In the above-mentioned method for producing a polypropylene composition,it is preferable to use a preactivated catalyst for olefinpolymerization obtained by a process comprising polymerizing olefin inthe presence of a catalyst for polyolefin production comprising atransition metal compound catalyst composition containing at least atitanium compound, 0.01 to 1,000 mole of an organic metal compound (AL1)of a metal selected from the group consisting of metals that belong togroup I, group II, group XII and group XIII of the periodic tablepublished in 1991 per 1 mole of the transition metal atom, and 0 to 500mole of an electron donor (E1) per 1 mole of the transition metal atomto preliminarily activate the catalyst and form 0.01 to 5,000 g ofpolypropylene having an intrinsic viscosity [77 A] of at least 0.01 dl/gbut less than 15 dl/g measured in tetralin at 135° C. per 1 g of thetransition metal compound catalyst composition, in which thepolypropylene is supported by the transition metal compound catalystcomposition.

Another method for producing a polyolefin composition according to thepresent invention comprises producing polypropylene having an intrinsicviscosity [ηP] of at least 0.01 dl/g but less than 15 dl/g measured intetralin at 135° C. in the presence of a catalyst for main olefinpolymerization comprising: a preactivated catalyst for olefinpolymerization obtained by a process comprising polymerizing olefin inthe presence of a catalyst for polyolefin production comprising atransition metal compound catalyst composition containing at least atitanium compound, 0.01 to 1,000 mole of an organic metal compound (AL1)of a metal selected from the group consisting of metals that belong togroup I, group II, group XII and group XIII of the periodic tablepublished in 1991 per 1 mole of the transition metal atom, and 0 to 500mole of an electron donor (E1) per 1 mole of the transition metal atomto preliminarily activate the catalyst and form 0.01 to 5,000 g ofpolypropylene having an intrinsic viscosity [ηA] of at least 0.01 dl/gbut less than 15 dl/g measured in tetralin at 135° C. per 1 g of thetransition metal compound catalyst composition, wherein thepolypropylene is supported by the transition metal compound catalystcomposition; an organic metal compound (AL2) of a metal selected fromthe group consisting of metals that belong to group I, group II, groupXII and group XIII of the periodic table published in 1991, the totalamount of the organic metal compound (AL2) combined with the organicmetal compound (AL1) contained in the preactivated catalyst being 0.05to 5,000 mole per 1 mole of the transition metal atom in thepreactivated catalyst; and an electron donor (E2), the total amount ofthe electron donor (E2) combined with the electron donor (E1) containedin the preactivated catalyst being 0 to 3,000 mole per 1 mole of thetransition metal atom in the preactivated catalyst; and then performingmelt mixing of the polypropylene with polyethylene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photomicrograph (75,000× magnification) of a polypropylenecomposition according to Example 1 of the present invention, which isobtained by observation by means of a transmission electron microscope(TEM).

FIG. 2 is a traced diagram with explanation clarifying thephotomicrograph of FIG. 1.

FIG. 3 is a TEM photomicrograph of a conventional polypropyleneaccording to Comparative Example 3.

FIG. 4 is a traced diagram explaining the photomicrograph of FIG. 3,which shows that no particles exist in the polypropylene.

FIG. 5 is a photomicrograph (75,000× magnification) of a polypropylenecomposition according to Example 4 of the present invention, which isobtained by observation by means of a transmission electron microscope(TEM).

FIG. 6 is a traced diagram with explanation clarifying thephotomicrograph of FIG. 5.

PREFERRED EMBODIMENTS OF THE INVENTION

In the specification, the term “polypropylene” refers to propylenehomopolymer, and propylene-olefin random copolymer or propylene-olefinblock copolymer containing 50 wt % or more of the propylenepolymerization unit. The term “polyethylene” refers to ethylenehomopolymer and ethylene-olefin random copolymer containing 50 wt % ormore of the ethylene polymerization unit. The term “polymerization”refers to homopolymerization and copolymerization.

The present invention will be described in detail as follows:

The polyethylene (a) used in the polypropylene composition of thepresent invention has an intrinsic viscosity [ηE] of at least 0.01 dl/gbut less than 15 dl/g measured in tetralin at 135° C., and is either anethylene homopolymer or an ethylene-olefin random copolymer containing50 wt % or more of the ethylene polymerization unit, preferably eitheran ethylene homopolymer or an ethylene-olefin random copolymercontaining 70 wt % or more of the ethylene polymerization unit, morepreferably either an ethylene homopolymer or an ethylene-olefin randomcopolymer containing 90 wt % or more of the ethylene polymerizationunit. These polymers may be used either alone or in combinations of twoor more.

In order to obtain a film excellent in transparency, the polyethylene(a) should have an intrinsic viscosity [ηE] of at least 0.01 dl/g butless than 15 dl/g, preferably 0.05 to 10 dl/g, more preferably 0.1 to 8dl/g. If the intrinsic viscosity [ηE] of the polyethylene (a) is notwithin the above-mentioned range, neck-in is caused and a sweeper rollmark is formed during the production of a polypropylene film, so thatthe productivity of the film is greatly reduced.

Furthermore, it is preferable that the polyethylene (a) contains 50 wt %or more, preferably 80 wt % or more, more preferably 90 wt % or more ofthe ethylene polymerization unit in order to obtain a film excellent intransparency and rigidity.

The olefins other than ethylene that are copolymerized with ethylene andfurther comprise the polyethylene (a) are not particularly limited, butit is preferable to use olefins having 3 to 12 carbon atoms. Examplesinclude propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene,4-methyl-1-pentene, 3-methyl-1-pentene and the like. These olefins maybe used either alone or in combination.

In the polypropylene composition of the present invention, furtherpreliminary activation treatment using other α-olefins such aspropylene, butene, or pentene is not restricted and may be performed, aslong as the polypropylene composition contains 0.01 to 5 weight parts ofthe polyethylene (A), which is contained at a rate of 0.01 to 5,000 gper 1 g of the transition metal compound catalyst composition and has anintrinsic viscosity [ηA] of at least 0.01 dl/g but less than 15 dl/gmeasured in tetralin at 135° C. In this case, the order of thepreliminary activation is not particularly limited.

The density of the polyethylene (a) is not particularly limited. Thepolyethylene preferably has a density of approximately 880 to 980 g/l.The polypropylene (b) of the polypropylene composition of the presentinvention has an intrinsic viscosity [ηP] of 0.2 to 10 dl/g measured intetralin at 135° C., and is either a propylene homopolymer, apropylene-olefin random copolymer, or a propylene-olefin block copolymercontaining 50 wt % or more of the propylene polymerization unit,preferably either a propylene homopolymer or a propylene-olefin randomcopolymer containing 90 wt % or more of the propylene polymerizationunit. These polymers may be used either alone or in combinations of twoor more.

Polypropylene having an intrinsic viscosity [ηP] of 0.2 to 10 dl/g,preferably 0.5 to 8 dl/g is used as the polypropylene (b) in order toimprove the productivity of a film.

The olefins other than propylene that are copolymerized with propyleneand further comprise the polypropylene (b) are not particularly limited,but it is preferable to use olefins having 2 to 12 carbon atoms.Examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene,1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene and the like. Theseolefins may be used either alone or in combinations of two or more.

The stereoregularity of the polypropylene (b) is not particularlylimited, and any crystalline polypropylene that achieves the object ofthe present invention can be used. However, for example, polypropylenehaving crystallinity of 0.80 to 0.99, preferably 0.85 to 0.99, morepreferably 0.90 to 0.99 with regard to isotactic pentad tacticity (mmmm)measured with ¹³C-NMR (nuclear magnetic resonance spectrum) is suitablyused.

The term “isotactic pentad tacticity” (mmmm) herein refers to isotactictacticity in a pentad unit in a polypropylene molecular chain, measuredby means of ¹³C-NMR, which was proposed by A. Zambelli et al.(Macromolecules 6,925 (1973)). The assignment of the peak in themeasuring spectrum is determined according to the method of assignmentdetermination proposed by A. Zambelli et al (Macromolecules 8,687(1975)). In this method, the assignment is determined by using a mixedsolution containing 20 wt % of polymer and comprising o-dichlorobenzeneand brombenzene-d5 in a ratio of 8:2 by weight, and measuring underconditions of 67.20 MHz at 130° C. For example, a JEOL-GX270NMR made byJEOL, Ltd. is used as the measuring device.

The polypropylene composition of the present invention comprises 0.001to 5 weight parts, preferably 0.004 to 3 weight parts, particularlypreferably 0.01 to 2 weight parts of the polyethylene (a) as mentionedabove, and 100 weight parts of the polypropylene (b) so that a filmexcellent in transparency and rigidity can be obtained and thepolypropylene composition can be produced with good productivity.

If the content of the polyethylene (a) is too small, a film excellent intransparency and rigidity cannot be obtained. If the polypropylenecomposition does not contain the polyethylene (a), powdery polypropyleneof aggregated fine particles is produced during the production of thepolypropylene composition, so that the productivity is reduced. When apolypropylene film is produced from such polypropylene compositions,neck-in may be caused and a sweeper roll mark is easily formed, and theproductivity is greatly reduced.

On the other hand, if the content of the polyethylene (a) is too large,a film excellent in transparency cannot be obtained.

Although the polypropylene composition of the present invention can beproduced by any method as long as the above-mentioned range issatisfied, it can be easily produced by a method comprising performingmain polymerization of propylene or propylene and other olefins in thepresence of a catalyst preliminarily activated with ethylene or ethyleneand other olefins as specified below.

Although the polypropylene composition of the present invention can beproduced by any method as long as the above-mentioned range issatisfied, it can be easily produced by a method comprising polymerizingpropylene or propylene and other olefins in the presence of a catalystpreliminarily activated with propylene or propylene and other olefins asspecified below to produce a powdery composition comprisingpolypropylene (a) and (b), and mixing the powdery composition withpolyethylene (c).

In this specification, the term “preliminary activation” refers toactivating the polymerization activity of a catalyst for polyolefinproduction prior to the main polymerization of propylene or propyleneand other olefins. It is performed by polymerizing ethylene or ethyleneand other olefins in the presence of a catalyst for polyolefinproduction and making the catalyst support the polymerized olefin.

The preactivated catalyst used in producing the polypropylenecomposition of the present invention comprises a catalyst for polyolefinproduction comprising: a transition metal compound catalyst compositioncontaining at least a titanium compound, 0.01 to 1,000 mole of anorganic metal compound (AL1) of a metal selected from the groupconsisting of metals that belong to Group I, Group II, Group XII, andGroup XIII of the periodic table published in 1991 per 1 mole of thetransition metal atom, and 0 to 500 mole of an electron donor (E1) per 1mole of the transition metal atom; and approximately 0.01 to 5,000 ofpolyethylene (A) having an intrinsic viscosity [ηA] of at least 0.01dl/g but less than 15 dl/g measured in tetralin at 135° C. per 1 g ofthe transition metal compound catalyst composition, which is supportedby the catalyst for polyolefin production.

In the preactivated catalyst, any known catalytic composition mainlycomprising a transition metal compound composition containing at least atitanium compound that has been proposed for producing polyolefin can beused as the transition metal compound catalyst composition.Particularly, a titanium-containing solid catalytic composition ispreferably used for ease of manufacture.

For example, titanium-containing solid catalytic compositions containinga titanium trichloride composition as a main component (JapanesePublished Examined Patent Applications (Tokko) No. SHO 56-3356, No. SHO59-28573, No. SHO 63-66323 and the like), supported titanium-containingcatalytic compositions containing titanium, magnesium, halogen andelectron donor as essential components where a magnesium compoundsupports titanium tetrachloride (Japanese Published Unexamined PatentApplications (Tokukai) No. SHO 62-104810, No. SHO 62-104811, No. SHO62-104812, No. SHO 57-63310, No. SHO 57-63311, No. SHO 58-83006, No. SHO58-138712 and the like) have been proposed, and any of these can be usedas the titanium-containing solid catalytic composition.

The organic metal compound (AL1) can be a compound having an organicgroup of a metal selected from the group consisting of metals thatbelong to Group I, Group II, Group XII, and Group XIII of the periodictable published in 1991. Examples include organic lithium compounds,organic sodium compounds, organic magnesium compounds, organic zinccompounds and organic aluminum compounds. The organic metal compound canbe used in combination with the above-mentioned transition metalcompound catalytic composition. From among the examples, it ispreferable to use an organic aluminum compound represented by thefollowing formula:

AlR¹ _(p)R² _(q)X_((3−(p+q)))

wherein R¹ and R² are independently selected from hydrocarbon groupssuch as alkyl group, cycloalkyl group and aryl group, and an alkoxygroup; X represents a halogen atom; and p and q are positive integerssatisfying a formula 0<p+q≦3.

Examples of organic aluminum compounds include trialkyl aluminums suchas trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum,tri-n-butyl aluminum, tri-i-butyl aluminum, tri-n-hexyl aluminum,tri-i-hexyl aluminum or tri-n-octyl aluminum; dialkyl aluminummonohalides such as diethyl aluminum chloride, di-n-propyl aluminumchloride, di-i-butyl aluminum chloride, diethyl aluminum bromide ordiethyl aluminum iodide; dialkyl aluminum hydrides such as diethylaluminum hydride; alkyl aluminum sesquihalide such as ethyl aluminumsesquichloride; monoalkyl aluminum dihalide such as ethyl aluminumdichloride; and alkoxyalkyl aluminum such as diethoxy monoethylaluminum, preferably trialkyl aluminum or dialkyl aluminum monohalide.Those organic aluminum compounds can be used either alone or incombination.

The electron donor (E1) is, if required, used to control formation rateand/or stereoregularity of polyolefin.

Examples of the electron donor (E1) include organic compounds having anyof oxygen, nitrogen, sulfur and phosphorus in the molecule, such asethers, alcohols, esters, aldehydes, fatty acids, ketones, nitrites,amines, amides, urea or thioureas, isocyanates, azo-compounds,phosphines, phosphites, hydrogen sulfide, thioethers or neoalcohols;silanols; and organic silicon compounds containing an Si—O—C bond in themolecule.

Examples of ethers include dimethyl ether, diethyl ether, di-n-propylether, di-n-butyl ether, di-i-amyl ether, di-n-pentyl ether, di-n-hexylether, di-i-hexyl ether, di-n-octyl ether, di-i-octyl ether,di-n-dodecyl ether, diphenyl ether, ethylene glycol monoethyl ether,diethylene glycol dimethyl ether, tetrahydrofuran and the like. Examplesof alcohols include methanol, ethanol, propanol, butanol, pentanol,hexanol, octanol, 2-ethyl hexanol, allyl alcohol, benzyl alcohol,ethylene glycol, glycerin and the like. Examples of phenols includephenol, cresol, xylenol, ethyl phenol, naphthol and the like.

Examples of esters include monocarboxylic acid esters such as methylmethacrylate, methyl formate, methyl acetate, methyl butyrate, ethylacetate, vinyl acetate, propyl-n-acetate, propyl-i-acetate, butylformate, amyl acetate, butyl-n-acetate, octyl acetate, phenyl acetate,ethyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate,butyl benzoate, octyl benzoate, 2-ethylhexyl benzoate, toluic acidmethyl ester, toluic acid ethyl ester, anisic acid methyl ester, anisicacid ethyl ester, anisic acid propyl ester, anisic acid phenyl ester,ethyl cinnamate, naphthoic acid methyl ester, naphthoic acid ethylester, naphthoic acid propyl ester, naphthoic acid butyl ester,2-ethylhexyl naphthoic acid, or ethyl phenylacetate; aliphaticpolycarboxylic acid esters such as diethyl succinate, methylmalonic aciddiethyl ester, butylmalonic acid diethyl ester, dibutyl maleate ordiethyl butylmaleic acid; and aromatic polycarboxylic acid esters suchas monomethyl phthalate, dimethyl phthalate, diethyl phthalate,di-n-propyl phthalate, mono-n-butyl phthalate, di-n-butyl phthalate,diisobutyl phthalate, di-n-heptyl phthalate, di-2-ethylhexyl phthalate,di-n-octyl phthalate, diethyl isophthalate, dipropyl isophthalate,dibutyl isophthalate, di-2-ethylhexyl isophthalate, diethylterephthalate, dipropyl terephthalate, dibutyl terephthalate ornaphthalenedicarboxylic acid diisobutyl ester.

Examples of aldehydes include acetaldehyde, propionaldehyde andbenzaldehyde. Examples of carboxylic acids include monocarboxylic acidssuch as formic acid, acetic acid, propionic acid, butyric acid, oxalicacid, succinic acid, acrylic acid, maleic acid, valeric acid or benzoicacid; and acid anhydrides such as benzoic anhydride, phthalic anhydrideor tetrahydrophthalic anhydride. Examples of ketones include acetone,methylethyl ketone, methylisobutyl ketone and benzophenone.

Examples of nitrogen-containing compounds include nitriles such asacetonitrile or benzonitrile; amines such as methyl amine, diethylamine, tributyl amine, triethanol amine, β-(N,N-dimethylamino)ethanol,pyridine, quinoline, α-picoline, 2,4,6-trimethyl pyridine,2,2,5,6-tetramethyl piperidine, 2,2,5,5-tetramethyl pyrrolidine,N,N,N′,N′-tetramethyl ethylenediamine, aniline or dimethyl aniline;amides such as formamide, hexamethyl phosphoric acid triamide,N,N,N′,N′,N″-pentamethyl-N′-β-dimethylaminomethyl phosphoric acidtriamide or octamethyl pyrophosphoryl amide; ureas such asN,N,N′,N′-tetramethyl urea; isocyanates such as phenyl isocyanate ortoluyl isocyanate; azo compounds such as azobenzene.

Examples of the phosphorus containing compounds include phosphines suchas ethyl phosphine, triethyl phosphine, di-n-octyl phosphine,tri-n-octyl phosphine, triphenyl phosphine or triphenyl phosphine oxide;phosphites such as dimethyl phosphite, di-n-octyl phosphite, triethylphosphite, tri-n-butyl phosphite or triphenyl phosphite.

Examples of the sulfur containing compounds include thioethers such asdiethyl thioether, diphenyl thioether or methyl phenyl thioether; andthioalcohols such as ethyl thioalcohol, n-propyl thioalcohol orthiophenol.

Examples of the organic silicon compounds include silanols such astrimethyl silanol, triethyl silanol or triphenyl silanol; and organicsilicon compounds having a Si—O—C bond, such as trimethylmethoxysilane,dimethyldimethoxysilane, methylphenyldimethoxysilane,diphenyldimethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane,phenyltrimethoxysilane, trimethylethoxysilane, dimethyldiethoxysilane,diisopropyldimethoxysilane, diisobutyldimethoxysilane,diphenyldiethoxysilane, methyltriethoxysilane, ethyltriethoxysilane,vinyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane,ethyltriisopropoxysilane, vinyltriacetoxysilane,cyclopentylmethyldimethoxysilane, cyclopentyltrimethoxysilane,dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane,cyclohexyltrimethoxysilane, dicyclohexyldimethoxysilane or2-norbornylmethyldimethoxysilane.

The above electron donors can be used either alone or in combination.

In the preactivated catalyst, the polyethylene (A) is either an ethylenehomopolymer or a copolymer of ethylene and olefins having 3 to 12 carbonatoms containing 50 wt % or more, preferably 70 wt % or more, morepreferably 90 wt % or more of the ethylene polymerization unit, whichhas an intrinsic viscosity [ηA] of at least 0.01 dl/g but less than 15dl/g, preferably 0.1 to 10 dl/g, more preferably 0.1 to 8 dl/g measuredin tetralin at 135° C. The polyethylene (A) eventually constitutes thepolyethylene (a) in the polypropylene composition of the presentinvention. Accordingly, the intrinsic viscosity [ηE] of the polyethylene(a) and the intrinsic viscosity [ηA] of the polyethylene (A) have arelationship of [ηE]=[ηA].

The amount of the polyethylene (A) to be supported by the catalyst is0.01 to 5,000 g, preferably 0.05 to 2,000 g, more preferably 0.1 to1,000 g per 1 g of the transition metal compound catalyst composition,so that a film having excellent transparency and rigidity can beobtained and a polypropylene composition can be produced with goodproductivity.

In the present invention, the preactivated catalyst is prepared by apreliminary activation treatment comprising polymerizing ethylene orethylene and other olefins in the presence of a catalyst for polyolefinproduction comprising the above-mentioned transition metal compoundcatalyst composition containing at least a titanium compound, an organicmetal compound (AL1) and, if required, an electron donor (E1) topreliminarily activate the catalyst and form the polyethylene (A), whichis supported by the transition metal compound catalyst composition.

The catalyst for polyolefin production used in the preliminaryactivation treatment comprises a transition metal compound catalystcomposition containing a titanium compound, and 0.01 to 1,000 mole,preferably 0.05 to 500 mole of an organic metal compound (AL1) per 1mole of the transition metal in the catalyst composition, and 0 to 500mole, preferably 0 to 100 mole of an electron donor (E1) per 1 mole ofthe transition metal in the catalyst composition.

In the catalyst for polyolefin production, the polyethylene (A) coversthe transition metal compound catalyst composition and is supported bythe catalyst composition by the process of: supplying 0.01 to 10,000 gof ethylene or a mixture of ethylene and other olefins in a solvent andpolymerizing in the presence of 0.001 to 5,000 millimole, preferably0.01 to 1,000 millimole, of the catalyst for polyolefin production per 1liter of polymerization volume of ethylene or ethylene and otherolefins, expressed in terms of the amount of transition metal atom inthe catalyst composition, to preliminarily activate the catalyst andform 0.01 to 5,000 g of polyethylene per 1 g of the transition metalcompound catalyst composition.

The term “polymerization volume” refers to a volume of the liquid phaseportion in a polymerization reactor with regard to liquid phasepolymerization, and to a volume of the gas phase portion in apolymerization reactor with regard to gas phase polymerization.

The amount of the transition metal compound catalyst composition used ispreferably within the above-mentioned range so as to maintain anefficient and controlled reaction rate of the propylene polymerization.Furthermore, if the amount of the organic metal compound (AL1) used istoo small, the polymerization reaction rate is inappropriately sloweddown. On the other hand, if the amount of the organic metal compoundused is too large, the polymerization reaction rate does notsufficiently increase, and in addition the polypropylene compositionobtained as a final product is likely to contain much residue of theorganic metal compound (AL1). Furthermore, if the amount of the electrondonor (E1) used is too large, the polymerization reaction rate isreduced. If the amount of the solvent used is too large, a large reactoris required and in addition it is difficult to control and maintain thepolymerization reaction rate efficiently.

The preliminary activation treatment can be performed in the liquidphase using solvents. Examples of the solvents include aliphatichydrocarbons such as butane, pentane, hexane, heptane, octane,isooctane, decane or dodecane; alicyclic hydrocarbons such ascyclopentane, cyclohexane or methyl cyclohexane; aromatic hydrocarbonssuch as toluene, xylene or ethylbenzene; inert solvents such as gasolinefraction or hydrogenized diesel oil fraction; and olefins. Furthermore,the preliminary activation treatment can also be performed in the gasphase without using a solvent.

The preliminary activation treatment may be performed in the presence ofhydrogen.

The conditions of the polymerization of ethylene or a mixture ofethylene and other olefins for preliminary activation of the catalystare not particularly restricted as long as the polyethylene (A) isproduced in an amount of 0.01 to 5,000 g, preferably 0.05 to 2,000 g,further preferably 0.1 to 1,000 g per 1 g of the transition metalcompound catalyst composition, and it is usually performed at arelatively low temperature of approximately −40 to 40° C., preferably−20 to 30° C., further preferably 0 to 20° C., at a pressure of 0.1 to 5MPa, preferably 0.2 to 5 MPa, more preferably 0.3 to 5 MPa, for 1 minuteto 24 hours, preferably 5 minutes to 18 hours, more preferably 10minutes to 12 hours.

To provide the intended polypropylene composition, the preactivatedcatalyst can be used as a catalyst for main polymerization of olefinshaving 2 to 12 carbon atoms, either alone or in combination withadditionally contained organic metal compound (AL2) and electron donor(E2).

The catalyst for main polymerization of olefins comprises theabove-mentioned preactivated catalyst, organic metal compound (AL2) andelectron donor (E2). The total amount of the organic metal compound(AL1) in the preactivated catalyst and the organic metal compound (AL2)is 0.05 to 3,000 mole, preferably 0.1 to 1,000 mole per 1 mole of thetransition metal atom in the preactivated catalyst. The total amount ofthe electron donor (E1) in the preactivated catalyst and the electrondonor (E2) is 0 to 5,000 mole, preferably 0 to 3,000 mole per 1 mole ofthe transition metal atom in the preactivated catalyst.

If the total amount of the organic metal compounds (AL1) and (AL2) istoo small, the reaction rate of the main polymerization of propylene orother olefins is inappropriately slowed down. On the other hand, if thetotal amount of the organic metal compounds (AL1) and (AL2) is toolarge, the polymerization reaction rate is not sufficiently increasedand is inefficient, and in addition undesirable large amounts of residueof the organic metal compound are contained in the polypropylenecomposition obtained as a final product. Furthermore, if the totalamount of the electron donors (E1) and (E2) is too large, thepolymerization reaction rate is greatly reduced.

The same types of compounds as those previously described for theorganic metal compound (AL1) and the electron donor (E1) may be used asthe organic metal compound (AL2) and the electron donor (E2),respectively, which are added as needed into the catalyst for the mainpolymerization of olefin. Furthermore, these compounds may be usedeither alone or in combinations of two or more. Still furthermore, theorganic metal compound (AL2) and the electron donor (E2) may be eitherof the same types as those used in the preliminary activation treatmentor of different types from those used in the preliminary activationtreatment.

The catalyst for main polymerization of olefin may be prepared as acombination of a powdery precipitate, or a suspension in which a solventis added to the powdery precipitate, and an organic metal compound (AL2)and, an electron donor (E2) as needed. The powdery precipitate is formedby removing the solvent, unreacted olefins, the organic metal compound(AL1), the electron donor (E1) and the like from the preactivatedcatalyst by filtration or decantation. Furthermore, the catalyst formain polymerization of olefin may also be prepared as a combination ofanother powdery precipitate, or a suspension in which a solvent is addedto the powdery precipitate, and an organic metal compound (AL2) and anelectron donor (E2) as required. The powdery precipitate in this case isformed by evaporating and removing the solvent and unreacted olefinsfrom the preactivated catalyst by reduced pressure distillation, inertgas flow or the like.

In the method of producing a polypropylene composition according to thepresent invention for use in polypropylene films, the amount of thepreactivated catalyst or the catalyst for main polymerization of olefinfor use is 0.001 to 1,000 millimole, preferably 0.005 to 500 millimoleper 1 liter of polymerization volume, expressed in terms of the amountof transition metal atom in the preactivated catalyst. By using thetransition metal compound catalyst composition within theabove-specified range, it is possible to maintain efficient andcontrolled polymerization reaction rate of propylene or a mixture ofpropylene and other olefins.

In the method of producing a polypropylene composition for use inpolypropylene films according to the present invention, the mainpolymerization of propylene or a mixture of propylene and other olefinscan be performed by a known polymerization process for olefins, such asslurry polymerization, bulk polymerization, gas phase polymerization,solution polymerization, or a combination of two or more types of theseprocesses. In the slurry polymerization, olefin is polymerized in aninert solvent, for example, aliphatic hydrocarbons such as propane,butane, pentane, hexane, heptane, octane, isooctane, decane, dodecane orthe like, alicyclic hydrocarbons such as cyclopentane, cyclohexane,methyl cyclohexane or the like, aromatic hydrocarbons such as toluene,xylene, ethylbenzene or the like, gasoline fraction or hydrogenizeddiesel oil fraction. In the bulk polymerization, the olefin is used as asolvent. In the gas phase polymerization, olefin is polymerized in gasphase. In the solution polymerization, the polyolefin formed bypolymerization is in liquid state.

In any polymerization process as described above, the polymerization isperformed under conditions of a temperature of 20 to 120° C., preferably30 to 100° C., more preferably 40 to 100° C., at a pressure of 0.1 to 5MPa, preferably 0.3 to 5 MPa and approximately for 5 minutes to 24 hoursof continuous, semi-continuous or batch polymerization. Under theabove-mentioned polymerization conditions, the polypropylene (b) can beproduced highly efficiently and with a controlled reaction rate.

In a further preferable embodiment of the method for producing apolypropylene composition of the present invention, the condition ofpolymerization is chosen so that the polypropylene (b) formed in themain polymerization and the polypropylene composition obtained as afinal product can have an intrinsic viscosity [ηr] of 0.2 to 10 dl/g,preferably 0.5 to 8 dl/g, and also so that the amount of thepolyethylene (A) derived from the preactivated catalyst contained in theobtained polypropylene composition is 0.001 to 5 wt %. Furthermore,similarly to known olefin polymerization methods, the molecular weightof the formed polymer can be adjusted by the use of hydrogen in thepolymerization.

After the main polymerization, known after-treatment processes such ascatalyst inactivation treatment, catalyst residue removing treatment,drying and the like are performed as needed, and the intendedpolypropylene composition having excellent transparency and rigidity isobtained.

In order to obtain powder, after the main polymerization, knownafter-treatment processes such as catalyst inactivation treatment,catalyst residue removing treatment, drying and the like are performedas needed, and powdery composition comprising polypropylene (a) and (b)can be obtained. The polypropylene composition of the present inventionis obtained, for example, by adding polyethylene (c) used in the presentinvention to the powdery composition, mixing it with a known mixingdevice, and performing melt mixing as required.

Another method for producing a propylene composition according to thepresent invention comprises polymerizing olefins in the presence of acatalyst for polyolefin production comprising a transition metalcompound catalyst composition containing at least a titanium compound,0.01 to 1,000 mole of an organic metal compound (AL1) of a metalselected from the group consisting of metals that belong to Group I ,Group II, Group XII, and Group XIII of the periodic table published in1991 per 1 mole of the transition metal atom, and 0 to 500 mole ofelectron donor (E1) per 1 mole of the transition metal atom topreliminarily activate the catalyst and form 0.001 to 5,000 g ofpolypropylene having an intrinsic viscosity [ηA] of at least 0.01 dl/gbut less than 15 dl/g measured in tetralin at 135° C. per 1 g of thetransition metal compound catalyst composition.

The intrinsic viscosity [ηA] of the polypropylene is at least 0.01 dl/gbut less than 15 dl/g, preferably 0.05 to 10 dl/g, more preferably 0.1to 8 dl/g so that a film excellent in transparency can be obtained. Ifthe intrinsic viscosity [ηA] of the polypropylene is far from theabove-mentioned range, neck-in is caused and a sweeper roll mark istransferred during production of films, and the productivity andtransparency of the film is greatly reduced. Furthermore, if the amountof the formed polypropylene is too small, aggregated and fine powderypolypropylene is formed during the production of polypropylene asdescribed below, and therefore it is inefficient in terms of costperformance.

In the preliminary activation treatment, as long as 0.001 to 5,000 g ofpolypropylene having an intrinsic viscosity [ηA] of at least 0.01 dl/gbut less than 15 dl/g is supported by a preactivated catalyst per 1 g ofthe transition metal compound catalyst composition, additionalpreliminary activation using other α-olefins such as propylene, butene,pentene and the like is not restricted and may be performed. In thiscase, the order of the preliminary activation is not particularlylimited.

Then, polypropylene having an intrinsic viscosity [ηP] of at least 0.01dl/g but less than 15 dl/g measured in tetralin at 135° C. is producedin the presence of a catalyst for the main polymerization of olefincomprising the preactivated catalyst for olefin polymerization, anorganic metal compound (AL2) of a metal selected from the groupconsisting of metals that belong to Group I, Group II, Group XII, andGroup XIII of the periodic table published in 1991, and electron donor(E2). The total amount of the organic metal compound (AL1) contained inthe preactivated catalyst and the organic metal compound (AL2) is 0.05to 5,000 mole per 1 mole of the transition metal atom in thepreactivated catalyst. The total amount of the electron donor (E1)contained in the preactivated catalyst and the electron donor (E2) is 0to 3,000 mole per 1 mole of the transition metal atom in thepreactivated catalyst. The intrinsic viscosity [ηP] of the polypropyleneis at least 0.01 dl/g but less than 15 dl/g, preferably 0.2 to 10 dl/g,more preferably 0.5 to 8 dl/g, so that the productivity in producing afilm is improved.

Finally, the polypropylene composition of the present invention can beobtained by mixing 100 weight parts of the polypropylene produced asdescribed above with at least 0.05 but less than 10 weight parts ofseparately-produced polyethylene, and performing melt mixing with anextruder or the like.

The mixed amount of the polyethylene is at least 0.05 but less than 10weight parts, preferably at least 0.05 but less than 5 weight parts,more preferably 0.05 to 1 weight parts so that a film excellent intransparency and rigidity can be obtained and a polypropylenecomposition having good productivity can be produced.

Hereinafter the present invention will be explained in further detailwith reference to examples and comparative examples.

Definition of the terms and measurement methods used in the examples andcomparative examples are as follows.

(1) Intrinsic viscosity [η]: values of the limiting viscosity intetralin at 135° C. measured with an Ostwald's viscometer produced byMitsui Toatsu Chemicals Inc. (unit: dl/g).

(2) Crystallization temperature (Tc): values measured with aPerkin-Elmer, Ltd. Differential Scanning Calorimetry VII of thetemperature indicating the maximum value of the heat absorption at thecrystallization of a polypropylene composition while raising thetemperature from the room temperature to 230° C. under a temperaturerise condition of 30° C./minute, maintaining the same temperature for 10minutes, lowering the temperature to −20° C. under the condition of −20°C./minute, maintaining the same temperature for 10 minutes, raising thetemperature to 230° C. under the temperature rise condition of 20°C./minute, maintaining the same temperature for 10 minutes, lowering thetemperature to 150° C. under the condition of −80° C./minute, andfurther lowering the temperature by −5° C./minute (unit: ° C.).

(3) Melting temperature (PP-T1): values measured with an ADACHI KEIKICo., Ltd. digital thermometer WO2866 right under a die of a temperatureof the molten resin extruded from the die at the same screw speed as theprocessing of a film produced by a T die method (unit: ° C.).

(4) Chilled roll temperature (PP-T2): values measured with a MINOLTACO., LTD. non-contact infrared thermometer 505 of a temperature of achilled roll (cooling roller) surface at the production of a film by a Tdie method (unit: ° C.).

(5) Film transparency: haze values measured according to ASTM D 1003 forfilms (unit: %). This is used as an indicator of transparency.

(6) Film rigidity: Young's modulus is measured according to ASTM D 882and used as an indicator of rigidity.

(7) Melt flow rates (MFR): melt flowability of a resin according to thecondition 14 in Table 1 of JIS K7210 (unit: g/10 minutes).

(8) Film spreadability: With regard to axial direction (lengthdirection) and mechanical flow direction (width direction) of a filmproduced by the inflation technique, the thickness in flow direction wasmeasured with a Dial Gage (product name) at 10 cm intervals, and thethickness in axial direction was measured at 1 m intervals for 50 m.Standard deviation was calculated for each of the obtained thicknessesin axial direction and in flow direction and then evaluated according tothe following standard. The smaller the standard deviation, the betterthe film spreadability.

(Standard of Spreadability)

∘: Both of the standard deviations of the thickness in axial directionand flow direction=less than 5%.

×: Either of the standard deviations of the thickness in axial directionor flow direction=5% or more.

(9) Impact resistance of a film: punching impact strength measuredaccording to ASTM D 781.

(10) Neck-in length: values measured with a metallic scale of the gapbetween the length of T die opening and the length of the obtained filmin the axial direction (unit: mm). The smaller the value of the neck-inlength, the smaller degree of the neck-in phenomenon occurred, so thatthe width of the film product having uniform thickness becomes large. Inorder to determine the effect of the polypropylene composition, thewidth of the lip opening of the T die was set to be constant (1.0 mm).

(11) Productivity: Productivity is ranked in accordance withspreadability, neck-in length, and in addition the standard ofappearance as mentioned below including irregular transparency in thefilm product (variation of haze value (Haze: ASTM D 1003) by 2% ormore). Particularly when irregular transparency is caused due toformation of sweeper roll mark, haze value varies by 3% or more, and thestandard of irregular transparency serves as the standard of formationof transferred sweeper roll mark.

(12) Standard of appearance

∘: no irregular transparency, wrinkling, unmolten materials andtransferred sweeper roll mark have been produced.

×: at least one of irregular transparency, wrinkling, unmolten materialsand transferred sweeper roll mark has been produced.

(13) Productivity was evaluated according to the ranking in thefollowing.

Productivity rank Spreadability Neck-in length(mm) Appearance 7 ∘ lessthan 40 ∘ 6 ∘ at least 40 but ∘ less than 100 5 ∘ 100 or more ∘ 4 ∘ lessthan 40 X 3 ∘ 40 or more X 2 X less than 40 X 1 X 40 or more X

A film of the rank not less than 6, preferably 7, has a highproductivity.

EXAMPLE 1

(1) Preparation of a Transition Metal Compound Catalyst Composition.

In a stainless steel polymerization reactor with an agitator, 0.3 literof decane, 48 g of magnesium chloride anhydride, 170 g oforthotitanate-n-butyl and 195 g of 2-ethyl-1-hexanol were mixedtogether, then dissolved while stirring at 130° C. for one hour to havea uniform solution. The uniform solution was heated to 70° C., then 18 gof di-i-butyl phthalate was added thereto while stirring. One hourlater, 520 g of silicon tetrachloride was added over a 2.5 hour periodto form a solid precipitate and further maintained at 70° C. for onehour. The solid was separated from the solution and washed with hexaneto obtain a solid product.

All the solid product was mixed with 1.5 liters of titaniumtetrachloride dissolved in 1.5 liters of 1,2-dichloroethane. Then, 36 gof di-i-butyl phthalate was added thereto and the mixture was allowed toreact for two hours at 100° C. while stirring. Then, the liquid phaseportion was eliminated by decantation at the same temperature, and 1.5liters of 1,2-dichloroethane and 1.5 liters of titanium tetrachloridewere added and maintained at 100° C. for two hours while kneading. Thenby washing with hexane and drying, a supported titanium containingcatalyst composition (transition metal compound catalyst composition)containing 2.8 weight % of titanium was obtained.

(2) Preparation of Preactivated Catalyst.

After replacing air in a 5 liter capacity stainless steel polymerizationreactor having an inclined-turbine agitator by a nitrogen gas, 2.8liters of n-hexane, 4 millimole of triethyl aluminum (organic metalcompound (AL1)) and 9.0 g of the supported titanium containing catalystcomposition prepared as mentioned above (5.26 millimole in terms of Tiatom) were added into the polymerization reactor. Then ethylene wascontinuously supplied into the reactor for two hours while maintainingthe temperature at 20° C. and the pressure at 0.59 MPa in the reactor tocarry out preliminary activating polymerization.

Separately, polymer formed in a preliminary polymerization performedwith the same conditions was analyzed and it was found that 2.0 g ofpolymer was formed per 1 g of the supported titanium containing catalystcomposition, and the intrinsic viscosity [ηT2] of the polymer measuredin tetralin at 135° C. was 6 dl/g.

After the reaction period, unreacted ethylene was discharged outside thereactor. Then, the gas phase portion in the polymerization reactor wasreplaced by a nitrogen gas one time to prepare a preactivated catalystslurry for main polymerization.

(3) Production of Polypropylene and a Polypropylene Composition.

After replacing air in a 500 liter capacity stainless steelpolymerization reactor having an agitator by a nitrogen gas, 240 litersof n-hexane, 780 millimole of triethyl aluminum (organic metal compound(AL2)), 78 millimole of diisopropyldimethoxysilane (electron donor (E2))and ½ amount of the preactivated catalyst slurry obtained as mentionedabove were added into the polymerization reactor at 20° C. Then afterintroducing 55 liters of hydrogen into the polymerization reactor andraising the temperature to 70° C., propylene was continuously suppliedfor two hours in the polymerization reactor under the condition of apolymerization temperature of 70° C. while maintaining the pressure ofthe gas phase portion in the reactor at 0.79 MPa, so that mainpolymerization of propylene was performed.

After the polymerization was complete, 1 liter of methanol wasintroduced to the polymerization reactor and the catalyst deactivationreaction was conducted at 70° C. for 15 minutes. Then after dischargingthe unreacted gas, the solvent was separated and polymer was dried toobtain 40.1 kg of polymer having an intrinsic viscosity [ηr] of 1.97dl/g. The polypropylene powder remained on 4-mesh at a rate of 0.05%,and the polypropylene powder passed through 70-mesh at a rate of 0.1%.

The polymer as obtained was found out to be a polypropylene compositioncontaining 0.008 weight % of the polyethylene (A) formed by preliminaryactivating polymerization, which corresponds to the component (a), andthe polypropylene (b) had an intrinsic viscosity [ηP] of 1.97 dl/g.

Using a Henschel mixer, 100 weight parts of the polypropylenecomposition obtained, 0.1 weight parts ofTetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, 0.1 weight parts of calcium stearate, 0.25 weight parts ofsilica having an average particle diameter of 1.7 μm, and 0.10 weightparts of erucin amide were mixed for two minutes. The mixture waspelletized at 230° C. using an extruder having a screw diameter of 65 mmto produce pellets. Various physical properties of the pellets weremeasured and evaluated to find that MFR and the crystallizationtemperature to be 4.5 g/10 minutes and 122.5° C., respectively.

The pellets were formed into a non-oriented film with a monolayer T diedevice having a screw diameter of 110 mm, an opening length of T die of1 m and lip opening width of 1.0 mm under the conditions of the melttemperature of 250° C., the water temperature passing through thechilled roll of 20° C., the thickness target of 15 μm, and the taking uprate of 200 m/min. The chilled roll temperature during the filmproduction was at 40° C., and the productivity of the obtained film was“7”. The properties of the film and the composition are shown in Table1.

The pellet as obtained was observed with a transmission electronmicroscope (TEM). The observation was performed as follows: a sample ofthe pellet was preheated for three minutes by thermal pressing at atemperature of 200° C., then press-molded at a pressure of 50 kg/cm² forfive minutes, and then solidified by cooling under pressure at atemperature of 50° C. under a pressure of 50 kg/cm² for three minutes toproduce a flat test piece having a thickness of 1 mm. The test piece wastrimmed and then electron staining with vapor of RuO₄ aqueous solutionwas performed to provide contrast for TEM observation. The RuO₄ aqueoussolution was prepared by dissolving 0.6 g of NaIO₄ made by Wako PureChemical industries, Ltd., guaranteed reagent, and 0.1 g of RuCl₃.nH₂Omade by Wako Pure Chemical industries, Ltd., into 10 ml of pure water.The test piece was put into a sealed container with the RuO₄ aqueoussolution and allowed to stand at room temperature for 48 hours, so thatstaining was performed.

Although the staining was carried out with vapor of the aqueous solutionin the present invention, it is also possible to perform it in a RuO₄aqueous solution or with a sublimation gas from RuO₄ crystal so as toobtain the same effect. The stained sample was processed into a sectionwith an ultramicrotome made by Japan Microtome Ltd., using a diamondknife having a knife angle of 45°, and an ultrathin section having athickness of about 80 nm was obtained. A sample of the ultrathin sectionwas observed using a TEM of JEM-100CX made by JEOL, Ltd. at anaccelerating voltage of 100 kV.

FIG. 1 shows a photomicrograph of 75000× magnification observed with theabove-mentioned TEM. As is evident from FIG. 1, the polymer of thisexample contained a polyethylene as dispersed fine particles having anumber average particle diameter of about 70 nm. Furthermore, it wasalso found out that the polyethylene had a lamellar structure.

FIG. 2 is a traced diagram having an explanation of a photograph in FIG.1. The explanation relates to globules and lamellar structure of highmolecular weight polyethylene. It is considered that the molecules ofthe polyethylene and the polypropylene interact with each other in someway. This appears to be a reason that a film having excellent rigidity,in which a sweeper roll mark is not transferred and little neck-in iscaused during the film production, and having high productivity can beobtained.

EXAMPLE 2

A polypropylene compositions was produced under the same conditions asExample 1 except that the conditions of the preliminary activatingpolymerization with ethylene were changed so as to change the formationamount of polyethylene (A). The powdery property of the obtainedpolypropylene composition was as follows: the polypropylene powderremained on 4-mesh at a rate of 0.07%, and the polypropylene powderpassed through 70-mesh at a rate of 0.2%.

Separately, polymer formed in preliminary polymerization performed inthe same conditions was analyzed and it was found that 1.0 g of polymerwas formed per 1 g of the supported titanium containing catalystcomposition, and the polymer had an intrinsic viscosity [ηT2] of 13 dl/gmeasured in tetralin at 135° C.

The polypropylene composition as obtained was processed into pellets asin Example 1 and formed into a film under the same conditions asExample 1. The productivity of the obtained film was “6”. The results ofthe evaluation of the film are shown in Table 1.

COMPARATIVE EXAMPLE 1

A polypropylene composition was produced using the same conditions asExample 1 except that the conditions of the preliminary activatingpolymerization with ethylene were changed so as to change the intrinsicviscosity of the polyethylene (A) in (2) in Example 1.

Separately, polymer formed in preliminary polymerization performed usingthe same conditions was analyzed and it was found that 2.0 g of polymerwas formed per 1 g of the supported titanium containing catalystcomposition, and the polymer had an intrinsic viscosity [ηT2] of 20 dl/gmeasured in tetralin at 135° C.

The obtained polypropylene composition had an intrinsic viscosity [ηr]of 1.70 dl/g. The powdery property of the polypropylene composition wasas follows: the polypropylene powder remained on 4-mesh at a rate of0.06%, and the polypropylene powder passed through 70-mesh at a rate of0.2%.

This polypropylene composition was processed into pellets as in Example1 and formed into a film under the same conditions as Example 1. Theobtained film had a productivity of “5”. The results of the evaluationof the film are shown in Table 1.

COMPARATIVE EXAMPLE 2

A polypropylene composition was produced using the same conditions asExample 1 except that the preliminary activating polymerization wasperformed with propylene instead of with ethylene in (2) in Example 1.

Separately, polymer formed in preliminary polymerization performed underthe same conditions was analyzed and it was found that 2.0 g of polymerwas formed per 1 g of the supported titanium containing catalystcomposition, and the polymer had an intrinsic viscosity [ηT2] of 2 dl/gmeasured in tetralin at 135° C.

The powdery property of the polypropylene composition as obtained was asfollows: the polypropylene powder remained on 4-mesh at a rate of 0.01%,and the polypropylene powder passed through 70-mesh at a rate of 0.05%.

The polypropylene composition was processed into pellets as in Example 1and formed into a film under the same conditions as Example 1. Theobtained film had a productivity of “1”. The results of the evaluationof the film are shown in Table 1.

COMPARATIVE EXAMPLE 3

A polypropylene composition was produced using the same conditions asExample 1 except that the preliminary activating polymerization withethylene was not performed in (2) in Example 1.

The polypropylene composition as obtained had an intrinsic viscosity[ηr] of 2 dl/g. The powdery property of the polypropylene compositionwas as follows: the polypropylene powder remained on 4-mesh at a rate of0.7%, and the polypropylene powder passed through 70-mesh at a rate of0.5%. This polypropylene composition was processed into pellets as inExample 1 and formed into a film under the same conditions as Example 1.The obtained film had a productivity of “3”. The results of theevaluation of the film are shown in Table 1.

The polymer pellets as obtained were observed with a transmissionelectron microscope (TEM) as in Example 1. As a result, it was found outthat a conventionally well-known polypropylene as the ComparativeExample 3 does not contain dispersed fine particles as shown in the TEMphotograph in FIG. 3 and the traced diagram thereof in FIG. 4.

EXAMPLE 3

A polypropylene composition was produced using the same conditions asExample 1 except that polymerization was performed in (3) as describedin the following.

(3) Production of Polypropylene Composition (Main Polymerization ofPropylene).

After replacing air in a 500 liter capacity stainless steelpolymerization reactor having an agitator by a nitrogen gas, 240 litersof n-hexane, 780 millimole of triethyl aluminum (organic metal compound(AL2)), 78 millimole of diisopropyldimethoxysilane (electron donor (E2))and ½ of the amount of the preactivated catalyst slurry as previouslyproduced were added into the polymerization reactor at 20° C.Subsequently, 55 liters of hydrogen were supplied to the polymerizationreactor and after the temperature was increased to 65° C.,propylene-ethylene co-polymerization was carried out while feedingcontinuously 1.3 kg of ethylene and propylene was continuously suppliedfor 2 hours, under conditions of a polymerization temperature of 65° C.and maintaining the pressure of the gas phase portion at 0.79 Mpa in thepolymerization reactor.

The powdery property of the polypropylene composition as obtained(ethylene content of 2.6%) was as follows: the ethylene-propylenecopolymer powder remained on 4-mesh at a rate of 0.3%, and theethylene-propylene copolymer powder passed through 70-mesh at a rate of0.01%.

This polypropylene composition was processed into pellets as in Example1 and formed into a film under the same conditions as Example 1. Theresults of the evaluation of the film are shown in Table 1. The obtainedfilm had a productivity of “6”.

COMPARATIVE EXAMPLE 4

A polypropylene composition was produced using the same conditions asExample 3 except that preliminary activating polymerization was carriedout with propylene instead of with ethylene in (2) in Example 3. Thepowdery property of the polypropylene composition as obtained (ethylenecontent of 2.0%) was as follows: the ethylene-propylene copolymer powderremained on 4-mesh at a rate of 0.5%, and the ethylene-propylenecopolymer powder passed through 70-mesh at a rate of 0.01%.

The polypropylene composition was processed into pellets as in Example 1and formed into a film under the same conditions as Example 1. Theresults of the evaluation of the film are shown in Table 1. The obtainedfilm had a productivity of “1”.

TABLE 1 Examples Comparative Examples Test items 1 2 3 1 2 3 4Preliminary Activation polyethylene A intrinsic viscosity 6 13 6 20 — —— [η] (dl/g) formation amount 2 1 2 2 — — — (g/g) polypropyleneintrinsic viscosity — — — — 2 — — [η] (dl/g) formation amount — — — — 2— — (g/g) Polypropylene Composition intrinsic viscosity 1.97 1.89 1.651.7 1.9 2 1.68 [η] (dl/g) ethylene content 0.008 0.004 2.6 0.006 — — 2.5(wt %) MFR 4.5 5.4 7 3.9 5.1 4.4 7.5 rate of powder 0.05 0.07 0.3 0.060.01 0.1 0.8 remained on 4-mesh (wt %) rate of powder passed 0.1 0.20.01 0.2 0.05 0.5 5 through 70-mesh (wt %) Film Properties transparency(haze) 4.4 4.6 3.8 10.5 8 6 5.2 (%) rigidity 960 965 580 990 870 880 520(Young's modulus) spreadability ◯ ◯ ◯ ◯ ◯ ◯ ◯ neck-in length 38 59 70110 150 130 180 (mm) appearance ◯ ◯ ◯ X X X X (IT: irregular (IT) (IT)(IT) (IT) transparency) productivity rank 7 6 6 5 1 3 3

EXAMPLES 4 to 6, COMPARATIVE EXAMPLE 5

(1) Preparation of a Transition Metal Compound Catalyst Composition.

In a stainless steel polymerization reactor with an agitator, 0.3 literof decane, 48 g of magnesium chloride anhydride, 170 g oforthotitanate-n-butyl and 195 g of 2-ethyl-1-hexanol were mixedtogether, then dissolved by heating at 130° C. for one hour whilestirring to provide a uniform solution. The uniform solution was heatedto 70° C., and 18 g of di-i-butyl phthalate was added thereto whilestirring. One hour later, 520 g of silicon tetrachloride was added overa 2.5 hour period to form a solid precipitate and further maintained at70° C. for one hour. The solid was separated from the solution andwashed with hexane to obtain a solid product.

All the solid product was mixed with 1.5 liters of titaniumtetrachloride dissolved in 1.5 liters of 1,2-dichloroethane. Then, 36 gof di-i-butyl phthalate was added thereto and the mixture was allowed toreact for two hours at 100° C. while stirring. Then, the liquid phaseportion was eliminated by decantation at the same temperature, and 1.5liters of 1,2-dichloroethane and 1.5 liters of titanium tetrachloridewere added and maintained at 100° C. for two hours while stirring. Thenby washing with hexane and drying, a supported titanium containingcatalyst composition (transition metal compound catalyst composition)containing 2.8 weight % of titanium was obtained.

(2) Preparation of Preactivated Catalyst.

After replacing air in a 5 liter capacity stainless steel polymerizationreactor having an inclined-turbine agitator by a nitrogen gas, 2.8liters of n-hexane, 4 millimole of triethyl aluminum (organic metalcompound (AL1)) and 9.0 g of the supported titanium containing catalystcomposition prepared as mentioned above (5.26 millimole in terms of Tiatom) were added into the polymerization reactor. Then, propylene wascontinuously supplied into the reactor for two hours while maintainingthe temperature at 20° C. and a pressure at 0.59 MPa in the reactor tocarry out preliminary activating polymerization.

Separately, polymer generated in a preliminary polymerization performedusing the same conditions was analyzed and it was found that 2.0 g ofpolymer was formed per 1 g of the supported titanium containing catalystcomposition, and the intrinsic viscosity [ηT2] of the polymer measuredin tetralin at 135° C. was 6 dl/g.

After the reaction period, unreacted propylene was discharged from thereactor. Then, the gas phase portion in the polymerization reactor wasreplaced by a nitrogen gas at one time to prepare a preactivatedcatalyst slurry for main polymerization.

(3) Production of Polypropylene and a Polyolefin Composition.

After replacing air in a 500 liter capacity stainless steelpolymerization reactor having an agitator by a nitrogen gas, 240 litersof n-hexane, 780 millimole of triethyl aluminum (organic metal compound(AL2)), 78 millimole of diisopropyldimethoxysilane (electron donor (E2))and ½ amount of the preactivated catalyst slurry obtained as mentionedabove were added into the polymerization reactor at 20° C. Then afterintroducing 55 liters of hydrogen into the polymerization reactor andraising the temperature to 70° C., propylene was continuously suppliedfor two hours in the polymerization reactor under the condition of thepolymerization temperature of 70° C. while maintaining the pressure ofthe gas phase portion in the reactor at 0.79 MPa, so that mainpolymerization of propylene was performed.

After the polymerization was complete, 1 liter of methanol wasintroduced to the polymerization reactor and the catalyst deactivationreaction was conducted at 70° C. for 15 minutes. Then after dischargingthe unreacted gas, the solvent was separated and polymer was dried toobtain 40.1 kg of polymer having an intrinsic viscosity [ηr] of 1.97dl/g. The polypropylene powder remained on 4-mesh at a rate of 0.05%,and the polypropylene powder passed through 70-mesh at a rate of 0.1%.

(4) Mixing of Polyethylene (c).

Pellets of polyethylene having a density of 0.956 g/cm³ and melt flowrate (190° C.: 21.18 n) of 18 g/10 min were added to the polypropylenepowder as obtained in such an amount that a composition with a ratio asshown in Table 2 can be obtained. Further, 0.1 weight % oftetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, 0.1 weight % of calcium stearate, 0.25 weight % of silicahaving an average particle diameter of 1.7 μm, and 0.10 weight % oferucic amide were admixed with the composition in this proportion, andmixed together with a Henschel mixer for two minutes. The mixture wasgranulated with an extruder having a screw diameter of 65 mm at 230° C.to produce pellets.

The pellets were formed into a non-oriented film with a monolayer T diedevice having a screw diameter of 110 mm, a T die opening length of 1 mand lip opening width of 1.0 mm, under the conditions of the melttemperature of 250° C., the water temperature passing through thechilled roll of 20° C., the thickness target of 25 μm, and the taking uprate of 200 m/min. The chilled roll temperature during the filmproduction was at 40° C. The properties of the obtained films and therespective compositions are shown in Table 2.

TABLE 2 Comparative Examples Example Test items 4 5 6 5 PreliminaryActivation polypropylene (a) intrinsic viscosity 6 6 6 6 [η] (dl/g)ratio in composition 0.00796 0.00736 0.007992 0.08 (Note 1)polypropylene (b) intrinsic viscosity 1.97 1.97 1.97 1.97 [η] (dl/g)ratio in composition 99.49204 91.99264 99.892008 99.992 (Note 1)Properties of polypropylene composition (a + b) powder remained on 0.050.05 0.05 0.05 4-mesh (wt %) powder passed through 0.1 0.1 0.1 0.170-mesh (wt %) polyethylene (c) density (g/cm³) 0.956 0.956 0.956 —ratio in composition 0.5 8 0.1 — (Note 1) Property of polyolefin 8 8.5 88 composition (a + b + c) MFR Properties of film transparency (haze) 2.82.76 2.9 3.3 (%) rigidity 900 1150 880 770 (Young's modulus) punchingimpact 0.5 0.4 0.9 1.2 strength (J) productivity rank 7 7 7 2 Note 1:ratio in composition comprising polyolefin (a + b + c) (wt %)

Furthermore, the polymer pellet obtained in Example 4 was observed witha transmission electron microscope (TEM) as in Example 1. FIG. 5 shows aphotomicrograph of 75000× magnification observed with theabove-mentioned TEM. As is evident from FIG. 5, the polymer of thisexample contained a polyethylene as dispersed fine particles having anumber average particle diameter of about 10 to 70 nm. Furthermore, itwas also found out that the polyethylene had a lamellar structure. FIG.6 is a traced diagram having an explanation of a photograph in FIG. 5.The explanation relates to globules and lamellar structure of highmolecular weight polyethylene. It is considered that the molecules ofthe polyethylene and the polypropylene interact with each other in someway. This appears to be a reason that a film having excellent rigidity,in which a sweeper roll mark is not transferred and little neck-in iscaused during the film production, and having high productivity can beobtained.

Industrial Applicability

As described above, the present invention provides a polypropylenecomposition from which a film excellent in transparency and rigidity andhaving high productivity, in which a sweeper roll mark is not formed andlittle neck-in is hardly caused during the production of the film, canbe obtained.

What is claimed is:
 1. A method for producing a polypropylenecomposition comprising polymerizing 100 weight parts of olefincomprising at least propylene in the presence of 0.001 to 10 weightparts of a preactivated catalyst comprising: a catalyst for polyolefinproduction comprising a supported titanium-containing catalyticcomposition comprising a magnesium compound supporting titaniumtetrachloride, 0.01 to 1,000 mole of an organic metal compound (AL1) ofa metal selected from the group consisting of metals that belong togroup I, group II, group XII and group XIII of the periodic tablepublished in 1991 per 1 mole of the transition metal atom, and 0 to 500mole of an electron donor (El) per 1 mole of the transition metal atom;and 0.01 to 5,000 g of polyethylene (A) having an intrinsic viscosity ofat least 0.01 dl/g but less than 15 dl/g measured in tetralin at 135° C.per 1 g of the transition metal compound catalyst composition; whereinthe olefin comprising at least propylene to be polymerized in thepresence of the preactivated catalyst is propylene or a mixture ofpropylene and other olefin, and a resultant polymer thereby is either apropylene homopolymer or a propylene-olefin random copolymer containing50 wt % or more of propylene polymerization unit, and wherein theintrinsic viscosity of the polypropylene composition measured intetralin at 135° C. is 0.2 to 15 dl/g and the polyethylene is finelydispersed as particles in the polypropylene composition.
 2. A method forproducing a polypropylene composition as claimed in claim 1, wherein thepolyethylene is finely dispersed as particles having a number averageparticle diameter of 1 to 5,000 nm.
 3. A method for producing apolypropylene composition as claimed in claim 2, wherein the numberaverage particle diameter of the polyethylene is 10 to 500 nm.
 4. Amethod for producing a polypropylene composition as claimed in claim 1,wherein the olefin comprising at least propylene to be polymerized inthe presence of the preactivated catalyst is propylene or a mixture ofpropylene and ethylene.
 5. A method for producing a polypropylenecomposition as claimed in claim 1, wherein the density of thepolyethylene is 0.93 to 0.960 g/cm³.
 6. A method for producing apolypropylene composition as claimed in claim 1, the polyethylene (A)being polymerized at a temperature between −20° C. and 30° C.
 7. Amethod for producing a polypropylene composition as claimed in claim 1,the polyethylene (A) being polymerized at a temperature between 0° C.and 20° C.
 8. A method for producing a polyolefin composition comprisingproducing polypropylene having an intrinsic viscosity of at least 0.2dl/g but less than 15 dl/g measured in tetralin at 135° C. in thepresence of a catalyst for main olefin polymerization comprising: apreactivated catalyst for olefin polymerization obtained by a processcomprising polymerizing ethylene in the presence of a catalyst forpolyolefin production comprising a supported titanium-containingcatalytic composition comprising a magnesium compound supportingtitanium tetrachloride, 0.01 to 1,000 mole of an organic metal compound(AL1) of a metal selected from the group consisting of metals thatbelong to group I, group II, group XII and group XIII of the periodictable published in 1991 per 1 mole of the transition metal atom, and 0to 500 mole of an electron donor (El) per 1 mole of the transition metalatom to preliminarily activate the catalyst and forming 0.001 to 5,000 gof polyethylene (A) having an intrinsic viscosity of at least 0.01 dl/gbut less than 15 dl/g measured in tetralin at 135° C. per 1 g of thetransition metal compound catalyst composition, wherein the polyethylene(A) is supported by the transition metal compound catalyst composition;an organic metal compound (AL2) of a metal selected from the groupconsisting of metals that belong to group I, group II, group XII andgroup XIII of the periodic table published in 1991, the total amount ofthe organic metal compound (AL2) combined with the organic metalcompound (AL1) contained in the preactivated catalyst being 0.05 to5,000 mole per 1 mole of the transition metal atom in the preactivatedcatalyst; and an electron donor (E2), the total amount of the electrondonor (E2) combined with the electron donor (E1) contained in thepreactivated catalyst being 0 to 3,000 mole per 1 mole of the transitionmetal atom in the preactivated catalyst, wherein the olefin is propyleneor a mixture of propylene and other olefin, and a resultant polymerthereby is either a propylene homopolymer or a propylene-olefin randomcopolymer containing 50 wt % or more of propylene polymerization unit.